Beverage containers for various soft drinks or beer are generally formed by drawn and iron technology (i.e., the DI can), in which the container trunk (or side wall portion) and the container bottom are integrally formed by drawing and ironing a metallic sheet, such as an aluminum alloy sheet or a surface-treated steel sheet.
In the industry, these beverage containers are produced massively and relatively economically to substantially an identical shape. As the containers are produced substantially to an identical shape, they can not adequately be discriminated or differentiated from one another by their appearance. As the beverage containers are manufactured massively and relatively economically, there is a strong desire among beverage manufacturers for economical beverage containers with unique configurations to help differentiate their products.
In an effort to satisfy the desires of the beverage manufacturers, many containers manufacturers have been trying to add improvements to their manufacturing technology and a number of processes for reshaping the container bodies have been proposed to date. One example of a prior reshaping process that produces a container body having an increased diameter includes molding technology in combination with an expansion medium that is positioned within the container body. The expansion medium causes a radial expansion of the container body from its interior against a mold surface having a geometry that corresponds to the desired shape. The expansion medium may include compressed air or nitrogen; an incompressible liquid; or may be provided by radially actuated fingers.
Reshaping or expansion of container bodies by molding technology has a number of disadvantages. More specifically, molding of container bodies increases manufacturing time and hence the cost associated with producing the beverage containers. Molding is not easily incorporated into an inline process, therefore requiring that the molding step be separate from the in line process of forming container bodies using drawn and iron technology.
A further disadvantage is that the degree of expansion that may be provided using molding is substantially limited, especially when taking into account that drawn and ironed cans have undergone intensive metal working, i.e., drawing and ironing operations, and may no longer retain adequate ductility so that a conspicuous contour to give the desired effects is attainable without resulting in rupture of the can or metal fracture. In one example, an aluminum body container having a wall thickness on the order of approximately 0.0040″, can only be radially expanded by a maximum of 10% of the container body's original diameter using a single molding step.
In light of the above, a need exists to provide a more economic method of providing beverage containers having an expanded diameter portion, wherein the method is easily incorporated into an in-line process.